In 3GPP (3rd Generation Partnership Project) which is a project aiming to standardize a mobile communication system, the standardization of LTE Advanced, which is a sophisticated version of LTE (Long Term Evolution), is conducted after 3GPP Release 10.
In the 3GPP Release 10, an LIPA (Local Internet Protocol Access) function by a home base station is defined (see NPLs 1 and 2). The home base station is a small-sized base station provided in a house or in a company and may be called a femto cell base station.
LIPA is a function of performing communication by an LIPA connection (LIPA PDN connection) which is established between a user terminal and a local device within an IP network of the house (or company) where the user terminal is located, via a home base station and not via a core network of an operator. The LIPA does not feed user data to the core network, and thus, it is possible to reduce a traffic load of the core network.
The 3GPP Release 10 does not support a mobility of the LIPA connection. Therefore, when a user terminal having the LIPA connection moves from a home base station to another base station, the connection is always released. As a result, when resuming communication between the user terminal and the local device to which the user terminal had been connected, a reconnection process is needed, and thus, the communication is interrupted.